Aquaculture Reports (Jun 2024)
The effect of partial replacement of calf fat and canola oil instead of dietary fish oil on growth performance, liver tissue, liver enzymes and chemical composition of young rainbow trout (Oncorhynchus mykiss)
Abstract
The aim of this research is to investigate the effects of substituting a portion of the fish oil in the diet of rainbow trout with calf fat and canola oil on their growth performance and chemical composition. To accomplish the desired goal, a total of 300 fish, with an average weight of 22.2 ± 0.6 g, were distributed evenly among 20 fibreglass ponds, each with a capacity of 500 liters. The fish were nourished over a period of 90 days. According to the obtained results, both the control group and the four experimental treatments showed the highest levels of weight growth, biomass increase, survival rate, and food conversion ratio. Treatment 3 demonstrated the most minimal increments in weight, specific growth rate, and daily growth index, along with the least efficient use of food, protein, and fat. Treatment 3 demonstrated the highest parametric values for protein synthesis and fat production, and these values were substantially distinct from those seen in the other experimental treatments. The chemical composition analysis demonstrated a statistically significant disparity in the moisture content between the fish in treatment 3 and the fish in the other treatments. Additionally, it was noted that the fish in treatments 3 and 4 had a much higher amount of fat in comparison to both the control treatment and treatment 2. Treatment 2 had the most minimal protein content among the fish. The results for the omega-6 group of fatty acids were consistent with the findings seen for the other important groups of fatty acids found in the oils used in this investigation. According to nutritionists' recommendations, all of the treatments examined in this study followed the recommended ratio of greater than 1:4. The fatty acid composition of all the treatments in this investigation may be deemed adequate in terms of both content and ratios. The present research showcases that rainbow salmon muscles have a high fat quality, which has promising advantages for human health. All therapies had positive effects in terms of the cholesterol index. The fish that were only given a diet of fish oil showed a considerable rise in the concentration of the LDH enzyme compared to the other groups that received different treatments. The present study found that the liver had steatosis in all treatment groups. To summarize, the use of a combination of animal fats, vegetable oils, and fish oil resulted in much better results compared to using each component alone. Therefore, considering the analyzed data, it is advisable to undertake treatment 4.
